U.S. patent application number 15/588368 was filed with the patent office on 2017-12-28 for methods and devices for deep vein thrombosis prevention.
The applicant listed for this patent is Kern S. BHUGRA, Thomas J. FOGARTY, Robert W. HORST. Invention is credited to Kern S. BHUGRA, Thomas J. FOGARTY, Robert W. HORST.
Application Number | 20170367918 15/588368 |
Document ID | / |
Family ID | 39686465 |
Filed Date | 2017-12-28 |
United States Patent
Application |
20170367918 |
Kind Code |
A1 |
HORST; Robert W. ; et
al. |
December 28, 2017 |
METHODS AND DEVICES FOR DEEP VEIN THROMBOSIS PREVENTION
Abstract
Portable devices and methods for preventing deep vein thrombosis
(DVT) by assuring that the ankle is flexed and extended
sufficiently to promote blood flow in the lower leg are disclosed.
The device includes an actuator with a free movement mode that
allows a patient to move freely between activations or to initiate
movement to delay a next automatic activation.
Inventors: |
HORST; Robert W.; (San Jose,
CA) ; BHUGRA; Kern S.; (San Jose, CA) ;
FOGARTY; Thomas J.; (Portola Valley, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HORST; Robert W.
BHUGRA; Kern S.
FOGARTY; Thomas J. |
San Jose
San Jose
Portola Valley |
CA
CA
CA |
US
US
US |
|
|
Family ID: |
39686465 |
Appl. No.: |
15/588368 |
Filed: |
May 5, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15273525 |
Sep 22, 2016 |
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15588368 |
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13683503 |
Nov 21, 2012 |
9474673 |
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15273525 |
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11932799 |
Oct 31, 2007 |
8353854 |
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13683503 |
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60901614 |
Feb 14, 2007 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61H 1/0218 20130101;
A63B 23/08 20130101; A61H 2201/149 20130101; A61H 1/00 20130101;
A61H 2201/1418 20130101; A63B 23/085 20130101; A61H 2201/1215
20130101; A63B 2220/16 20130101; A61H 2201/5069 20130101; A61H
2201/1676 20130101; A63B 2220/51 20130101; A63B 71/0622 20130101;
A61H 2201/5061 20130101; A61H 2201/1642 20130101; A61H 2201/5097
20130101; A61H 1/0266 20130101; A61H 2209/00 20130101 |
International
Class: |
A61H 1/02 20060101
A61H001/02 |
Claims
1. (canceled)
2. A device for free or controlled movement of a joint of a user,
comprising: a portable power supply; an embedded controller powered
by the portable power supply; an actuator having an output shaft
coupled to a first attachment and a second attachment, the actuator
controlled by the embedded controller to deliver a variable drive
force output mode for a first direction, a free-movement mode, and
a variable drive force output mode in a second direction that is
the opposite of the first direction; and a hinged connection
coupling the first attachment and the second attachment; wherein
the first attachment is configured for coupling to the output shaft
and to a first portion of the user and the second attachment is
configured for coupling to the output shaft and to a second portion
of the user.
3. The device of claim 2 further comprising a force sensor
configured to provide an indication to the embedded controller
related to the variable drive force in the first direction, the
variable drive force in the second direction or a force generated
while in the free movement mode.
4. The device of claim 2 further comprising a wireless charger with
a portable power supply.
5. The device of claim 2 further comprising a connection port
configured for wireless communication between a control unit and
the embedded controller.
6. The device of claim 2 the actuator further comprising a first
motor driven lead screw, a second motor driven lead screw and a
motor driven cam coupled to the first motor driven lead screw and
the second motor driven lead screw wherein coordinated operation of
the first motor driven lead screw, the second motor driven lead
screw and the motor driven cam drive the motion of output
shaft.
7. The device of claim 6 wherein the motion of the output shaft is
in the first direction and drives relative movement of the first
attachment point and the second attachment point relative to the
hinge to cause flexion of a joint of the user between the first
attachment point and the second attachment point.
8. The device of claim 7 wherein the embedded controller collects
and stores in memory data related to the movement of the actuator
in the first direction.
9. The device of claim 6 wherein the motion of the output shaft is
in the second direction and drives relative movement of the first
attachment point and the second attachment point relative to the
hinge to cause extension of a joint of the user between the first
attachment point and the second attachment point.
10. The device of claim 9 wherein the embedded controller collects
and stores in memory data related to the movement of the actuator
in the second direction.
11. The device of claim 6 wherein the motion of the output shaft is
in a free motion mode and the actuator permits relative movement of
the first attachment point and the second attachment point relative
to the hinge to permit user initiated movement of a joint of the
user between the first attachment point and the second attachment
point.
12. The device of claim 11 wherein the embedded controller collects
and stores in memory data related to the movement of the actuator
in the free motion mode.
13. The device of claim 3 further comprising a joint angle sensor
in communication with the embedded controller and positioned to
measure the angle between the first attachment or the second
attachment or the movement of the hinge.
14. The device of claim 3 wherein the first attachment is adapted
for securement to a superior aspect of a joint and the second
attachment is adapted for securement to an inferior aspect of a
joint.
15. The device of claim 3 wherein the joint is a joint of the
leg.
16. The device of claim 15 wherein the joint of the leg is an
ankle.
17. The device of claim 15 wherein the joint of the leg is a knee.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 15/273,525, filed Sep. 22, 2016, titled
"METHODS AND DEVICES FOR DEEP VEIN THROMBOSIS PREVENTION," which is
a continuation of U.S. patent application Ser. No. 13/683,503,
filed Nov. 21, 2012, titled "METHODS AND DEVICES FOR DEEP VEIN
THROMBOSIS PREVENTION," now U.S. Patent Application Publication No.
2013/0079687, which is a divisional application of U.S. patent
application Ser. No. 11/932,799, filed Oct. 31, 2007, titled
"METHODS AND DEVICES FOR MOVING A BODY JOINT," now U.S. Pat. No.
8,353,854, which claims priority to U.S. Provisional Patent
Application No. 60/901,614, filed Feb. 14, 2007, titled "DEEP VEIN
THROMBOSIS PREVENTION DEVICE," the contents of which are expressly
incorporated by reference herein.
INCORPORATION BY REFERENCE
[0002] All publications and patent applications mentioned in this
specification are herein incorporated by reference to the same
extent as if each individual publication or patent application was
specifically and individually indicated to be incorporated by
reference.
[0003] Deep Vein Thrombosis (DVT) is the formation of a thrombus
(clot) in a deep vein in a leg. The clot can block blood flow in
the leg, or the clot may travel to the lungs causing a potentially
fatal pulmonary embolism. The incidence of DVT is particularly high
after hip or knee surgery, but may occur whenever patients are
immobilized over a period of time. DVT occurrence is known to be
high after lower extremity paralysis due to stroke or injury and is
also a risk factor in pregnancy, obesity, and other conditions.
[0004] Current techniques for avoiding DVT have drawbacks. For
example, blood thinning drugs have side effects, elastic stockings
and compression devices have limited effectiveness, while
compression and exercise devices have limited patient compliance.
Active or passive movement of the ankle, alone or in combination
with other DVT avoidance techniques, can reduce the incidence of
DVT; however there has been no device to assure adequate movement
that is acceptable to hospital patients and staff.
SUMMARY OF THE INVENTION
[0005] The present invention teaches a variety of methods,
techniques and devices for preventing deep vein thrombosis (DVT).
According to one embodiment, a DVT prevention device is attached to
a patient's ankle, or any portion of any limb, to deliver active or
passive movement to promote blood flow in the lower extremities.
According to certain aspects, the DVT prevention device includes a
battery or AC-powered actuator, an embedded computer, a software
control system, sensors, and a coupling to the ankle and the
foot.
[0006] According to another embodiment, a DVT prevention device
operates in one or more modes to supply 1) passive extension and
flexion of the ankle, 2) active extension and flexion of the ankle,
and 3) free movement of the ankle. Patient compliance may be
enhanced by allowing the patient to determine the preferred mode of
operation; the device assures adequate total movement over a period
of time by supplying passive movement when necessary. For example,
the patient may perform enough movements in free-movement mode to
delay future activations of the device, or the patient may actively
resist the movement to exercise the calf muscles and promote
enhanced blood flow beyond that of passive movement.
[0007] According to yet another aspect of the present invention,
the present invention may include an output connection to allow the
patient's extension and flexion of the ankle to serve as a human
interface device similar to a computer mouse. If coupled to a web
browser or computer game, the device can serve the dual role of
preventing DVT and helping the patient to pass time more quickly.
Such a device can also serve as the primary input device to those
with arm or hand disabilities and may tend to avoid or mitigate
carpal tunnel syndrome.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a block diagram of electronics and an embedded
computer that controls a deep vein THROMBOSIS (DVT) prevention
device according to an embodiment of the present invention.
[0009] FIG. 2a shows a front view of a DVT prevention device
attached to the leg of a patient according to an embodiment of the
present invention.
[0010] FIG. 2b shows a side view of the DVT prevention device of
FIG. 2a near the flexion limit.
[0011] FIG. 2c shows a side view of the DVT prevention device near
the extension limit.
[0012] FIG. 3. shows a continuously variable actuator according to
another aspect of the present invention that may be used to
construct a DVT prevention device.
[0013] FIG. 4. shows a single-motor actuator with a free movement
mode according to another embodiment of the present invention.
[0014] FIG. 5. shows a single-motor actuator as attached to an
ankle according to a further embodiment of the present
invention.
[0015] FIG. 6. is a flowchart of a method for the prevention of DVT
according to one aspect of the present invention.
DETAILED DESCRIPTION
[0016] FIG. 1 shows a block diagram of a deep vein THROMBOSIS (DVT)
prevention device 100 according to an embodiment of the present
invention. An embedded microcontroller 102 is programmed to accept
input from one or more sensors such as joint angle sensor 104 and a
force (e.g., current) sensor 106. The embedded microcontroller 102
may also be coupled to a control panel 108. The control panel 108
may be for use by a patient, a doctor, or other health care
provider. The embedded microcontroller 102 is operable to produce
outputs for power drivers 112 to control the motion of one or more
actuators 114.
[0017] With further reference to FIG. 1, power is supplied to the
DVT prevention device 100 through an actuator power supply 116.
Power may come through a battery 118 or from an AC adapter 120. In
one embodiment, the battery 118 is wirelessly recharged by
inductive coupling to a pad conveniently placed, such as at the
foot of a hospital bed. Such a wireless recharge device has been
announced by Wildcharge at the 2007 Consumer Electronics show.
[0018] In certain embodiments, such as cases where the patient can
supply significant force to exercise the ankle, the battery
charging requirements may be reduced or eliminated by recharging
the battery from energy captured from running the actuator 114 as
backdriven motor generator. This may provide an extra incentive to
the patient to exercise, especially if the amount of exercise is
recorded and presented to the patient, the patient's family and the
hospital staff.
[0019] The control panel 108 may be as simple as an on/off switch,
or may include switches and displays to allow adjustments for the
range of motion, minimum repetition frequency, movement statistics,
battery charge, and the like.
[0020] One embodiment includes a USB or wireless connection 122 to
allow the DVT prevention device 100, or a pair of devices (e.g.,
one device each on the left and right ankles), to act as a human
interface device (HID) that may be connected, for instance, to a
PC. For example, the right ankle position may determine the
left/right location of a computer curser and the left ankle
position may determine the up/down location of the curser. When a
patient uses the computer, for instance to surf the internet or
play a game, the ankles must be flexed and extended, and in the
process the blood flow to the leg is enhanced. The computer
connection may significantly enhance patient compliance, which is a
major problem with existing compression devices.
[0021] FIG. 2 shows three views of a DVT prevention device 200,
according to another embodiment of the present invention, attached
to an ankle 202. An actuator 204 is attached to upper and lower
ankle attachment points such that activation of the actuator 204
may extend or flex the ankle 202. FIG. 2a shows a front view of the
DVT prevention device 200, FIG. 2b shows a side view of the DVT
prevention device 200 near a flexion limit, and FIG. 2c shows a
side view of the DVT prevention device 200 near an extension limit.
The limits may be programmatically or physically limited within the
patient's range of motion. As will be appreciated, a typical
extension limit (also known as Planar Flexion) is about 45 degrees
from the standing position of the ankle, and a typical flexion
limit (also known as Doral Flexion) is about -20 degrees from the
standing position.
[0022] With further reference to FIG. 2, a rigid foot support
structure 206 is placed under the foot and a rigid ankle support
208 structure is placed behind the calf. The two support structures
206 and 208 are connected to each other with a hinge 210. The
actuator 204 is mounted to the upper rigid structure 208. Straps or
padded supports 212 hold the ankle support structure 208 and
actuator 204 to the lower leg. An output shaft 214 of the actuator
204 is connected to a linkage 216 attached to the foot support
structure 206. One or more straps 212 hold the foot support
structure 206 to the foot.
[0023] FIG. 3 shows a continuously variable actuator 300 suitable
for use as an actuator according to certain embodiments of the
present invention. One suitable example of the continuously
variable actuator is described in more detail in the Horst et al.'s
U.S. patent application Ser. No. 11/649,493, filed Jan. 3, 2007,
the contents of which are incorporated herein by reference. The
actuator 300 uses a flexible belt 302 connected by belt supports
304 and 306, two motor-driven lead screws 308 and 310 driven by
motors 312 and 314, respectively, and a motor driven cam 316 driven
by motor 318 to provide variable drive ratio forces in either
direction or to allow the output shaft 320 to move in a
free-movement mode. Also shown are two driven carriages 322 and
324, and two passive carriages 326 and 328.
[0024] FIG. 4 shows a single-motor actuator 400 suitable for use as
an actuator according to another embodiment the present invention.
In the single-motor actuator 400, a motor 402, which may have an
internal gear head, drives a lead screw 404 to move a nut 406
linearly. The lead screw 404 may be an acme screw, a ball screw
with a ball nut for lower friction and higher motor efficiency, or
any other suitable screw. The ball nut 406 is always between a
flexion stop 408 and an extension stop 410 connected to an output
shaft 412. When the ball nut 406 is in a center of travel, the
output shaft 412 is free to move linearly in either direction
without having movement impeded by interaction with the ball nut
406. This position provides free movement of the output shaft 412,
and likewise free movement of the ankle or other relevant body
part, even with no power applied to the actuator 400. When it is
time to extend or flex the ankle, the ball screw 404 is turned to
move the ball nut 406 to the left or the right where the ball nut
406 eventually pushes against the flexion or extension stop.
Further movement of the ball nut 406 in the same direction moves
the flexion stop 408 or the extension stop 410, and hence moves the
output shaft 412, thus causing the ankle to flex or extend,
respectively. The output shaft 412 is supported by one or more
linear bearings 414 allowing the output shaft 412 to move freely in
one dimension while preventing substantial movement or twisting in
other dimensions
[0025] To further elaborate, lead screws include types of screws
such as acme screws and ball screws. Ball screws have nuts with
recirculating ball bearings allowing them to be backdriven more
easily than acme screws. When using a ball screw, motion of the nut
causes the lead screw and hence the motor to rotate. Therefore,
when the ball nut is engaged by one of the stops, the patient may
exercise the leg muscles by extending or flexing the foot to cause
motion of the output shaft and hence cause motion of the motor.
Exercise may be accomplished either by resisting the passive
motions imparted by the actuator, or through a separate exercise
mode where all motion is caused by the patient. In either case,
software running in the embedded processor controls the amount of
current delivered to/from the motor and therefore the amount of
exercise resistance
[0026] FIG. 5 shows the single motor actuator 400 of FIG. 4
attached to an ankle support 212 and coupled to a foot support 206
through a linkage 216. The ball screw 404 in the actuator 400 is
shown in a position about to extend the ankle by pushing to the
right. Near the extension and flexion limits, some compliance may
be built in to provide more comfort to the patient and to assure
that there is no possibility of injuring the patent. This may be
accomplished by springs in the actuator 400 or springs in the
linkage 216, or both (not shown), that expand or compress before
damaging forces are applied
[0027] To further elaborate, a free-movement mode of the actuator
400 allows the patient to move the ankle with little resistance.
The free movement mode obviates the need to remove the DVT
prevention device when walking (for instance, to the restroom);
this improves patient compliance because there is no need for the
patient or hospital staff to remove and reattach the DVT protection
device frequently.
[0028] FIG. 6 is a flowchart of a method for operating a device in
the prevention of DVT according to one embodiment of the present
invention. In step 602, a person such as a medical professional
sets up the device with appropriate limits for range of motion and
minimum time between ankle movements. This step 602 may also be
performed automatically. Then, in step 604, a DVT prevention device
is attached to one or both ankles of the patient, and if necessary
the device is turned on. In step 606, a test is made to determine
if too much time has elapsed since the last flexion of the ankle.
If the predefined time limit between flexion has been exceeded,
step 608 runs a device actuator through one flexion/extension cycle
or other suitable sequence. This cycle may be purely passive
motion, or the patient may actively resist tending to cause more
blood flow. If the time limit has not been exceeded or if the cycle
is at the end of the passive or active movement cycle, the actuator
is put into free movement mode in step 610. Finally, in step 612,
the movements of the ankle are monitored to help determine the
appropriate time for the next movement. Step 612 is followed by
step 606, repeating the sequence until the prevention method stops,
the device is removed, or the device is turned off.
[0029] In the flowchart of FIG. 6, step 606 determines if the
specified time has elapsed in order to initiate movement of the
ankle. The "specified time" can be determined by any suitable
manner including one or more of any of the following ways: [0029]
1. A fixed elapsed time since the last ankle movement [0030] 2. A
moving average over time of the frequency of ankle movements.
[0031] 3. A dynamic algorithm that approximates blood flow in the
leg by taking into account the frequency of movement, the intensity
of active movement, and the patients age and condition.
[0030] A fixed time algorithm is simplest to implement, but may
move the ankle more than necessary. Using a frequency of movement
algorithm, the patient can have more control and has more positive
feedback for initiating movements beyond the minimum. A dynamic
algorithm rewards patient-initiated exercise (resisting the passive
movement) and also customizes the frequency of movement based on
the patient's condition. The algorithm can be determined through
clinical studies of different patients using the device while
monitoring blood flow.
[0031] The invention is not limited to the specific embodiments
described. For example, actuators need only have a way to move and
allow free movement of the ankle and need not have strictly linear
movement. The actuator may be driven from a brushed or brushless
motor or may be activated through pneumatics, hydraulics,
piezoelectric activation, electro-active polymers or other
artificial muscle technology. The usage of the device is not
confined to hospitals but also may be beneficial to those bedridden
in nursing homes or at home. The device may also be beneficial to
avoid DVT for those traveling long distances by airplane,
automobile or train.
* * * * *